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* [Bug rtl-optimization/67221] New: ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1)
@ 2015-08-14 18:09 su at cs dot ucdavis.edu
2015-08-14 18:10 ` [Bug rtl-optimization/67221] " mpolacek at gcc dot gnu.org
` (6 more replies)
0 siblings, 7 replies; 8+ messages in thread
From: su at cs dot ucdavis.edu @ 2015-08-14 18:09 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67221
Bug ID: 67221
Summary: ICE at -Os and above on x86_64-linux-gnu: Segmentation
fault (program cc1)
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: su at cs dot ucdavis.edu
Target Milestone: ---
The following (valid) code causes an ICE when compiled with the current gcc
trunk at -Os and above on x86_64-linux-gnu in both 32-bit and 64-bit modes.
It is a regression from 5.1.x.
$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --prefix=/usr/local/gcc-trunk
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 6.0.0 20150813 (experimental) [trunk revision 226872] (GCC)
$
$ gcc-trunk -O1 -c small.c
$ gcc-5.1 -Os -c small.c
$
$ gcc-trunk -Os -c small.c
gcc-trunk: internal compiler error: Segmentation fault (program cc1)
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.
$
----------------------------------
int a, b;
int
fn1 (int p)
{
return 0 == 0 ? p : 0;
}
void
fn2 ()
{
int c = 1, d[1] = { 1 };
lbl:
for (;;)
{
int e;
c ? 0 : 0 / c;
c = 0;
if (fn1 (d[0]))
break;
for (e = 0; e < 1; e++)
for (c = 1; b;)
{
if (a)
break;
goto lbl;
}
}
}
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug rtl-optimization/67221] ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1)
2015-08-14 18:09 [Bug rtl-optimization/67221] New: ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1) su at cs dot ucdavis.edu
@ 2015-08-14 18:10 ` mpolacek at gcc dot gnu.org
2015-08-14 18:17 ` trippels at gcc dot gnu.org
` (5 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2015-08-14 18:10 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67221
Marek Polacek <mpolacek at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2015-08-14
CC| |mpolacek at gcc dot gnu.org
Target Milestone|--- |6.0
Ever confirmed|0 |1
--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Confirmed.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug rtl-optimization/67221] ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1)
2015-08-14 18:09 [Bug rtl-optimization/67221] New: ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1) su at cs dot ucdavis.edu
2015-08-14 18:10 ` [Bug rtl-optimization/67221] " mpolacek at gcc dot gnu.org
@ 2015-08-14 18:17 ` trippels at gcc dot gnu.org
2015-08-14 20:09 ` mpolacek at gcc dot gnu.org
` (4 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: trippels at gcc dot gnu.org @ 2015-08-14 18:17 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67221
Markus Trippelsdorf <trippels at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |trippels at gcc dot gnu.org
--- Comment #2 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
Looks like a stack overflow in gimple-match.c.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug rtl-optimization/67221] ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1)
2015-08-14 18:09 [Bug rtl-optimization/67221] New: ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1) su at cs dot ucdavis.edu
2015-08-14 18:10 ` [Bug rtl-optimization/67221] " mpolacek at gcc dot gnu.org
2015-08-14 18:17 ` trippels at gcc dot gnu.org
@ 2015-08-14 20:09 ` mpolacek at gcc dot gnu.org
2015-08-17 7:31 ` [Bug tree-optimization/67221] [6 Regression] " rguenth at gcc dot gnu.org
` (3 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: mpolacek at gcc dot gnu.org @ 2015-08-14 20:09 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67221
--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Started with r226850.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/67221] [6 Regression] ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1)
2015-08-14 18:09 [Bug rtl-optimization/67221] New: ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1) su at cs dot ucdavis.edu
` (2 preceding siblings ...)
2015-08-14 20:09 ` mpolacek at gcc dot gnu.org
@ 2015-08-17 7:31 ` rguenth at gcc dot gnu.org
2015-08-17 8:25 ` rguenth at gcc dot gnu.org
` (2 subsequent siblings)
6 siblings, 0 replies; 8+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-08-17 7:31 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67221
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org
Summary|ICE at -Os and above on |[6 Regression] ICE at -Os
|x86_64-linux-gnu: |and above on
|Segmentation fault (program |x86_64-linux-gnu:
|cc1) |Segmentation fault (program
| |cc1)
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
Mine.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/67221] [6 Regression] ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1)
2015-08-14 18:09 [Bug rtl-optimization/67221] New: ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1) su at cs dot ucdavis.edu
` (3 preceding siblings ...)
2015-08-17 7:31 ` [Bug tree-optimization/67221] [6 Regression] " rguenth at gcc dot gnu.org
@ 2015-08-17 8:25 ` rguenth at gcc dot gnu.org
2015-08-17 14:18 ` rguenth at gcc dot gnu.org
2015-08-17 14:18 ` rguenth at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-08-17 8:25 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67221
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Ok, so we have
e_17 = e_3 + 1;
and e_3 value-numbers to e_17 (for some reason). match-and-simplify then
recursively matches ((e_3 + 1) + 1) + 1 ...
Visiting BB 8
SCC consists of: e_3 e_17
Starting iteration 1
Value numbering e_3 stmt = e_3 = PHI <0(5), e_17(8)>
Setting value number of e_3 to c_2 (changed)
Value numbering e_17 stmt = e_17 = e_3 + 1;
Setting value number of e_17 to e_17 (changed)
Starting iteration 2
Value numbering e_3 stmt = e_3 = PHI <0(5), e_17(8)>
Setting value number of e_3 to e_17 (changed)
Oops. This isn't supposed to happen. Ok - so the only executable edge
is the backedge here (should have catched that block as unexecutable, sth
to fix as well). Hmm, we only forbid a VARING -> non-VARYING lattice
transition, not a transition from one value to another. Fishy.
Of course even with the old PHI value-numbering we should have arrived
at e_3 == e_17 and the very same problem (problem being using the backedge
value as "same val" and the entry edge not executable).
Value numbering e_17 stmt = e_17 = e_3 + 1;
So the workaround I am installing is to mark backedges into unreachable
blocks unexecutable as well. Still the reason the def of e_17 is not
found unreachable is (again) in sub-optimal visiting order of the
DOM walk :(
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/67221] [6 Regression] ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1)
2015-08-14 18:09 [Bug rtl-optimization/67221] New: ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1) su at cs dot ucdavis.edu
` (4 preceding siblings ...)
2015-08-17 8:25 ` rguenth at gcc dot gnu.org
@ 2015-08-17 14:18 ` rguenth at gcc dot gnu.org
2015-08-17 14:18 ` rguenth at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-08-17 14:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67221
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
Author: rguenth
Date: Mon Aug 17 14:17:33 2015
New Revision: 226938
URL: https://gcc.gnu.org/viewcvs?rev=226938&root=gcc&view=rev
Log:
2015-08-17 Richard Biener <rguenther@suse.de>
PR tree-optimization/67221
* tree-ssa-sccvn.c (visit_phi): Keep all-TOP args TOP.
(sccvn_dom_walker::before_dom_children): Mark backedges of
non-executable blocks as not executable.
* gcc.dg/torture/pr67221.c: New testcase.
Added:
trunk/gcc/testsuite/gcc.dg/torture/pr67221.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/testsuite/ChangeLog
trunk/gcc/tree-ssa-sccvn.c
^ permalink raw reply [flat|nested] 8+ messages in thread
* [Bug tree-optimization/67221] [6 Regression] ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1)
2015-08-14 18:09 [Bug rtl-optimization/67221] New: ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1) su at cs dot ucdavis.edu
` (5 preceding siblings ...)
2015-08-17 14:18 ` rguenth at gcc dot gnu.org
@ 2015-08-17 14:18 ` rguenth at gcc dot gnu.org
6 siblings, 0 replies; 8+ messages in thread
From: rguenth at gcc dot gnu.org @ 2015-08-17 14:18 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67221
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |RESOLVED
Resolution|--- |FIXED
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed.
^ permalink raw reply [flat|nested] 8+ messages in thread
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2015-08-14 18:09 [Bug rtl-optimization/67221] New: ICE at -Os and above on x86_64-linux-gnu: Segmentation fault (program cc1) su at cs dot ucdavis.edu
2015-08-14 18:10 ` [Bug rtl-optimization/67221] " mpolacek at gcc dot gnu.org
2015-08-14 18:17 ` trippels at gcc dot gnu.org
2015-08-14 20:09 ` mpolacek at gcc dot gnu.org
2015-08-17 7:31 ` [Bug tree-optimization/67221] [6 Regression] " rguenth at gcc dot gnu.org
2015-08-17 8:25 ` rguenth at gcc dot gnu.org
2015-08-17 14:18 ` rguenth at gcc dot gnu.org
2015-08-17 14:18 ` rguenth at gcc dot gnu.org
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